Australian Federal Police commissioner Reece Kershaw signalled the agency would wrap up all its contractual agreements with the firm last August, and officials confirmed on Tuesday that this was now in effect.

Chief Financial Officer Paul Wood told Greens senator Barbara Pocock the government had paid a total sum of $627,999 to the firm as a "compensation payment", explaining none of this was a penalty, but was all for work undertaken by the firm.

While PwC Australia sold off its government advisory business last year, it still operates its auditing business.

"The AFP did determine a range of contracts with PwC with effect of the June 30, 2023. We signed that deed on the July 3, 2023," Mr Wood said.

"We had contracts for an organisational health solution, there were several audits ... they were the AFP's internal audit provider, and they were also working on an IT solution called a privileged access management solution."

The AFP is still conducting an investigation into the firm, after Treasury made a referral on May 24 last year.

It relates to allegations that PwC Australia's former head of international tax Peter-John Collins shared confidential information from a Treasury briefing with other staff and partners.

In January 2023, the Tax Practitioner's Board banned Mr Collins from practising as a tax agent for two years. In May, emails tabled in Parliament alleged 63 people had received the confidential information, prompting Treasury to refer the matter to the AFP.

Known as Operation Alesia, the investigation is "complex", and is being treated as a priority, Deputy Commissioner Ian McCartney said, in response to questions from Liberal senator Richard Colbeck and Senator Pocock.

"It's an investigation that the AFP is proceeding as a priority, in terms of a priority investigation, but given the fact that it's ongoing, Senator [Colbeck], I don't think it's appropriate to ventilate those issues in terms of the progress of the investigation," Deputy Commissioner McCartney said.

The investigation is being overseen by the Sensitive Investigation Board, he said.

Its scope is "both domestic and international", but the Deputy Commissioner would not comment on the number of individuals being investigated.

He also declined to provide a potential timeline for the investigation, saying, "I don't think I can give you a definitive timing when these matters traditionally take a considerable amount of time."

Australian Federal Police Commissioner Reece Kershaw said the complexity of such investigations required painstaking effort from officers.

"When you have a criminal investigation involving, as in, as the Deputy said, very complex issues ... it's really hard for the investigators to make a sterile corridor to keep that brief of evidence away from any future challenge or complications," Commissioner Kershaw said.

"So the team have to painstakingly go through every piece of material, they have to literally analyse it in depth, you have to have a legal team attached all the way along. It's extremely complex.

"But you know, whilst it may be not satisfying for the timeline, we will get to the bottom of it at the end of the day, it's just going to take a while."